The director was spotted looking thoughtfully at Harry Benson’s iconic photograph of Farrow and Sinatra entering Truman Capote’s Black and White Ball, which was on display at the Holden Luntz Gallery’s stand at the Park Avenue Armory art and antiques show Thursday.

An onlooker told us, “Woody just stood there looking at the photo of Mia Farrow and Frank Sinatra, studying it intently. He didn’t say a word. Eventually, he quietly moved on.”

The photo — of a masked, elfin Farrow and an angry-looking Sinatra entering Capote’s Ball at the Plaza Hotel — was taken by famed Scottish photographer Benson in 1966. Allen began a relationship with Farrow around 1980, and the couple separated in 1992 over the Soon-Yi affair.

Last week, over two decades later, Farrow got her revenge by revealing in Vanity Fair that Frank, not Woody, might be the father of her biological son, Lil’ Blue Eyes Ronan Farrow.